1. Field of the Invention and Related Art Statement
The present invention relates to an apparatus for recording and/or reproducing data or information on and/or from an optical card.
In the above mentioned recording and/or reproducing apparatus using the optical card, the recording and/or reproducing operation is carried out by moving the optical card having a plurality of tracks arranged in parallel with each other and an optical head including an objective lens for projecting a recording and/or reproducing light beam onto the optical card relative to each other in a reciprocal manner.
FIG. 1 is a plan view showing schematically an example of the optical card for use in the above mentioned recording and/or reproducing apparatus. An optical card 1 includes a plurality of tracks 2 which extend in a direction parallel to a longer side of the rectangular sheet-like optical card in parallel with each other. As illustrated in FIG. 2, each of the tracks 2 of a preformatted optical card consists of ID portions provided on both ends of the track and a data portion situating between the ID portions, the data being recorded in said data portion. The ID portions include ID marks 3a and 3b,respectively indicating start points of the ID portions and ID regions 4a and 4b,respectively indicating track information such as a track address. In the present optical card, the data portion includes four sectors 6a, 6b, 6c and 6d divided by five sector marks 5a, 5b, 5c, 5d and 5e. Usually these ID portions and sector marks have been pre-recorded on the optical card 1. In order to make an area of the data record region as wide as possible, the ID portions are not provided for each sectors.
When the above mentioned optical card is actually used, an amount of the data to be recorded in a track, i.e., data portion, on the optical card varies in accordance with particular applications. Therefore, in order to utilize efficiently the data record region having a limited area, it is necessary to prepare a number of track formats each having different sector sizes or lengths suitable for respective applications. In one solution for this it may be conceived that plural kinds of the sector marks are pre-recorded on a single optical card to from a plurality of track formats each having different sector lengths. However, in such an optical card, tracks having the sector sizes which are not suitable for an application are not used and thus the data record region is wasted.
In order to solve the above mentioned drawback, in Japanese Patent Laid-open Publication Kokai Sho No. 63-4476, there is proposed a recording and/or reproducing apparatus using an optical card having tracks, in which a plurality of independent data are recorded in a single track without pre-recorded sector marks for dividing the track into a plurality of sectors. In this known data recording and/or reproducing apparatus, there are formed two different kinds of tracks, one being a data track which is composed of a single sector and the other being a directory track in which a plurality of independent data for managing the recorded condition of data tracks are recorded. A known method of recording a plurality of directory data on the directory track will then be explained with reference to FIGS. 3A to 3D. FIG. 3A depicts a reproduced signal which is obtained by scanning the directory track and FIG. 3B shows an output signal of a retriggable one-shot multivibrator to which the reproduced signal is supplied. High level of the output signal of this multivibrator indicates that an area in which a single directory data block has been recorded is just reproduced. FIG. 3C illustrates a signal which is generated in response to a trailing edge of the output signal shown in FIG. 3B and lasts for a predetermined time period which corresponds to an interval between successive directory data blocks. FIG. 3D shows a new directory data block which is to be recorded on the optical card next to the last directory data block. This directory data block is generated in response to a trailing edge of the signal shown in FIG. 3C. In this manner, a start point for recording a new directory data block is determined on the basis of the end of a last recorded data block in the same track.
The known recording and/or reproducing apparatus disclosed in the above mentioned Japanese Patent Laid-open Publication Kokai Sho No.63-4476 has a problem in that an access time is liable to be long. That is to say, in the optical card, in order to shorten the access time, it is preferable that the recording and/or reproducing is effected in opposite directions of the relative movement of the optical card and optical head in a reciprocal manner. However, in the known apparatus the recording start point is determined by detecting the end point of the last recorded sector, so that the recording and/or reproducing can be performed only in one predetermined direction. This results in an increase in the the access time. Further, in the known apparatus the recording has to be effected orderly, and thus it is impossible to record a third directory data block after recording a first directory data block without recording a second directory data block. In other words, when the above explained data recording method is applied to record data in a plurality of sectors in a data track, it is impossible to record data in arbitrary sectors in the track in a random order.